Solid state imaging device, method of manufacturing solid-state imaging device, and electronic apparatus

ABSTRACT

The present technique aims to provide a solid-state imaging device that reduces shading and color mixing between pixels. The present invention also provides a method of manufacturing the solid-state imaging device. The present technique further relates to a solid-state imaging device that enables provision of an electronic apparatus that uses the solid-state imaging device, a method of manufacturing the solid-state imaging device, and an electronic apparatus. The solid-state imaging device includes a substrate, pixels each including a photoelectric conversion unit formed in the substrate, and a color filter layer formed on the light incidence surface side of the substrate. The solid-state imaging device also includes a device isolating portion that is formed to divide the color filter layer and the substrate for the respective pixels, and has a lower refractive index than the refractive indexes of the color filter layer and the substrate.

This application is a continuation of U.S. patent application Ser. No.17/337,827, filed Jun. 3, 2021, which is a continuation of U.S. patentapplication Ser. No. 16/864,811, filed May 1, 2020, now U.S. Pat. No.11,032,497, which is a continuation of U.S. patent application Ser. No.16/415,501, filed May 17, 2019, now U.S. Pat. No. 10,651,223, which is acontinuation of U.S. patent application Ser. No. 16/218,402, filed Dec.12, 2018, now U.S. Pat. No. 10,593,720, which is a continuation of U.S.patent application Ser. No. 15/720,134, filed Sep. 29, 2017, now U.S.Pat. No. 10,319,770, which is a continuation of U.S. patent applicationSer. No. 15/261,450, filed Sep. 9, 2016, now U.S. Pat. No. 9,812,485,which is a continuation of U.S. patent application Ser. No. 14/417,027,filed Jan. 23, 2015, now U.S. Pat. No. 9,496,303, which is a nationalstage application under 35 U.S.C. 371 and claims the benefit of PCTApplication No. PCT/JP2013/069509 having an international filing date ofJul. 18, 2013, which designated the United States, which PCT applicationclaimed the benefit of Japanese Patent Application No. 2012-168365 filedJul. 30, 2012, the disclosures of the above-identified applications areincorporated herein by reference.

TECHNICAL FIELD

The present technique relates to solid-state imaging devices, methods ofmanufacturing solid-state imaging devices, and electronic apparatuses,and more particularly, to a solid-state imaging device of aback-illuminated type, a method of manufacturing the solid-state imagingdevice, and an electronic apparatus using the solid-state imagingdevice.

BACKGROUND ART

In a conventional solid-state imaging device, light-gathering on-chiplenses corresponding to respective pixels are provided on the lightreceiving surface side of a substrate. Light that is gathered by theon-chip lenses enters the light receiving units of the respective pixelsformed in the substrate, and signal charges in accordance with theamounts of light are generated at the light receiving units.

The tilt of a principal ray that enters the solid-state imaging devicevia an imaging optical system provided in an imaging apparatus or thelike becomes greater in the periphery of the pixel region. Therefore, atthe pixels in the periphery of the pixel region formed in thesolid-state imaging device, light gathered by the corresponding on-chiplenses does not enter the central portions of the light receiving units.

To counter this problem, Patent Document 1 discloses a technique bywhich the pitch of the on-chip lenses corresponding to the lightreceiving units of the respective pixels becomes narrower toward theperiphery of the pixel region, compared with the pitch of the lightreceiving units. With this arrangement, shading correction is performed.As the pitch of the on-chip lenses is made to differ between the centralregion of the pixel region and the periphery of the pixel region, lightthat enters obliquely can be gathered into the central portion of eachlight receiving unit in the periphery of the pixel region.

Meanwhile, so as to improve photoelectric conversion efficiency andsensitivity to incident light, a solid-state imaging device of aso-called back-illuminated type has been recently suggested. In asolid-state imaging device of a back-illuminated type, a drive circuitis formed on the surface side of a semiconductor substrate, and the backsurface of the semiconductor substrate serves as the light receivingsurface. As an interconnect layer is provided on the opposite side ofthe substrate from the light receiving surface in the solid-stateimaging device of the back-illuminated type, the distance between thelight receiving units formed in the substrate and the surfaces of theon-chip lenses provided on the light incidence side of the substratebecomes shorter, and accordingly, sensitivity is increased.

Patent Document 2 discloses a solid-state imaging device of aback-illuminated type in which a trench is formed to a predetermineddepth from the light receiving surface (back surface) of the substrateso as to reduce color mixing, and photodiode regions are isolated fromone another by burying an insulating material in the trench. As therespective photodiode regions are isolated from one another by theinsulating material buried in the trench, electrons generated in aphotodiode region do not leak into an adjacent photodiode region, andcolor mixing can be reduced.

CITATION LIST Patent Document

-   Patent Document 1: JP 01-213079 A-   Patent Document 2: JP 2010-225818 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In a solid-state imaging device of a back-illuminated type, colorfilters are normally formed on the light receiving surface side of thesubstrate, and on-chip lenses are formed on the color filters, as in asolid-state imaging device of a front-illuminated type. In a solid-stateimaging device of a back-illuminated type, the distance from thesurfaces of the on-chip lenses to the light receiving surface of thesubstrate is shorter than that in a solid-state imaging device of afront-illuminated type, and accordingly, sensitivity is increased asdescribed above. However, in the periphery of the pixel region in asolid-state imaging device of a back-illuminated type, shading due tooblique incident light might occur, or color mixing might be caused dueto oblique light entering an adjacent pixel between color filters.

In view of the above aspects, the present disclosure aims to provide asolid-state imaging device that reduces shading and color mixing betweenpixels. The present disclosure also aims to provide a method ofmanufacturing the solid-state imaging device, and an electronicapparatus using the solid-state imaging device.

Solutions to Problems

A solid-state imaging device of the present disclosure includes asubstrate, pixels each including a photoelectric conversion unit formedin the substrate, and a color filter layer formed on the light incidencesurface side of the substrate. The solid-state imaging device of thepresent disclosure also includes a device isolating portion that isformed to divide the color filter layer and the substrate for therespective pixels, and has a lower refractive index than the refractiveindexes of the color filter layer and the substrate.

As the device isolating portion is formed in the color filter layer andthe substrate in the solid-state imaging device of the presentdisclosure, adjacent pixels are optically and electrically isolated fromone another. As the device isolating portion is designed to have a lowerrefractive index than the refractive indexes of the color filter layerand the substrate, oblique light is prevented from entering an adjacentpixel, and light that enters the device isolating portion is gatheredinto the photoelectric conversion units of the respective pixels.

A method of manufacturing a solid-state imaging device of the presentdisclosure includes: the step of forming photoelectric conversion unitsin a substrate, the photoelectric conversion units corresponding torespective pixels; and the step of forming a color filter layer on thelight incidence surface side of the substrate. The method ofmanufacturing a solid-state imaging device of the present disclosurealso includes the step of forming a device isolating portion in theregion to divide the color filter layer and the substrate for therespective pixels, the device isolating portion having a lowerrefractive index than the refractive indexes of the color filter layerand the substrate, the device isolating portion being formed prior to orafter the formation of the color filter layer.

By the method of manufacturing the solid-state imaging device of thepresent disclosure, the device isolating portion that isolates therespective pixels from one another is formed in the color filter layerand the substrate. Accordingly, adjacent pixels are optically andelectrically isolated from one another. The device isolating portion isdesigned to have a lower refractive index than the refractive indexes ofthe color filter layer and the substrate. Accordingly, oblique light isprevented from entering an adjacent pixel.

An electronic apparatus of the present disclosure includes the abovedescribed solid-state imaging device and a signal processing circuitthat processes an output signal that is output from the solid-stateimaging device.

Effects of the Invention

According to the present disclosure, a solid-state imaging device thatreduces shading and color mixing between adjacent pixels is obtained.With the use of this solid-state imaging device, an electronic apparatuswith improved image quality can be obtained.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing an entire solid-state imagingdevice of a CMOS (Complementary Metal Oxide Semiconductor) typeaccording to a first embodiment of the present disclosure.

FIG. 2 is a cross-sectional view of the structure in the pixel region ofthe solid-state imaging device according to the first embodiment of thepresent disclosure.

FIGS. 3A through 3C are process charts (a first half) showing a methodof manufacturing the solid-state imaging device according to the firstembodiment of the present disclosure.

FIGS. 4D and 4E are process charts (a second half) showing the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present disclosure.

FIG. 5 is a cross-sectional view of the structure in the pixel region ofa solid-state imaging device according to a second embodiment of thepresent disclosure.

FIG. 6 is a cross-sectional view of the structure in the pixel region ofa solid-state imaging device according to a third embodiment of thepresent disclosure.

FIGS. 7A and 7B are process charts showing a method of manufacturing thesolid-state imaging device according to the third embodiment of thepresent disclosure.

FIG. 8 is a process chart showing another example of a method ofmanufacturing the solid-state imaging device according to the thirdembodiment of the present disclosure.

FIG. 9 is a cross-sectional view of the structure in the pixel region ofa solid-state imaging device according to a fourth embodiment of thepresent disclosure.

FIG. 10 is a cross-sectional view of the structure in the pixel regionof a solid-state imaging device according to a fifth embodiment of thepresent disclosure.

FIG. 11 is a cross-sectional view of the structure in the pixel regionof a solid-state imaging device according to a sixth embodiment of thepresent disclosure.

FIG. 12 is a cross-sectional view of the structure in the pixel regionof a solid-state imaging device according to a seventh embodiment of thepresent disclosure.

FIG. 13 is a cross-sectional view of the structure in the pixel regionof a solid-state imaging device according to an eighth embodiment of thepresent disclosure.

FIG. 14 is a cross-sectional view of the structure in the pixel regionof a solid-state imaging device according to a ninth embodiment of thepresent disclosure.

FIG. 15 is a cross-sectional view of the structure in the pixel regionof a solid-state imaging device according to a tenth embodiment of thepresent disclosure.

FIG. 16 is a schematic view of the structure of an electronic apparatusaccording to an eleventh embodiment of the present disclosure.

MODES FOR CARRYING OUT THE INVENTION

The following is a description of solid-state imaging devices accordingto embodiments of the present disclosure, methods of manufacturing thesolid-state imaging devices, and an example of an electronic apparatus,with reference to FIGS. 1 through 16 . Embodiments of the presentdisclosure will be explained in the following order. However, thepresent disclosure is not limited to the examples described below.

-   -   1. First embodiment: a solid-state imaging device    -   1-1. Structure of the entire solid-state imaging device    -   1-2. Structures of main components    -   1-3. Manufacturing method    -   2. Second embodiment: an example where a pixel isolating portion        is provided on a substrate    -   3. Third embodiment: a (first) example where a device isolating        portion is hollow    -   3-1. Structures of main components    -   3-2. Manufacturing method    -   3-3. Modification    -   4. Fourth embodiment: a (second) example where a device        isolating portion is hollow    -   5. Fifth embodiment: an example where the color filter layers        are made thicker    -   6. Sixth embodiment: an example where a light scattering        structure is provided    -   7. Seventh embodiment: an example where a light absorbing        portion is provided    -   8. Eighth embodiment: a (first) example where high-refractive        material portions are provided    -   9. Ninth embodiment: a (second) example where high-refractive        material portions are provided    -   10. Tenth embodiment: an example where on-chip lenses are        provided    -   11. Eleventh embodiment: an electronic apparatus

1. First Embodiment: Solid-State Imaging Device

[1-1. Structure of the Entire Solid-State Imaging Device]

First, a solid-state imaging device according to a first embodiment ofthe present disclosure is described. FIG. 1 is a schematic view of theentire structure of a CMOS solid-state imaging device according to thefirst embodiment of the present disclosure.

The solid-state imaging device 1 of this embodiment is designed toinclude a pixel region 3 formed with pixels 2 arranged on a substrate 11made of silicon, a vertical drive circuit 4, column signal processingcircuits 5, a horizontal drive circuit 6, an output circuit 7, and acontrol circuit 8.

As will be described later, the pixels 2 are designed to includephotoelectric conversion units formed with photodiodes, and pixeltransistors, and are regularly arranged in a two-dimensional array inthe substrate 11. The pixel transistors forming the pixels 2 may betransfer transistors, reset transistors, select transistors, andamplifying transistors, for example.

The pixel region 3 is formed with the pixels 2 regularly arranged in atwo-dimensional array. The pixel region 3 includes an effective pixelregion that actually receives light, amplifies signal charges generatedthrough photoelectric conversion, and reads out the signal charges tothe column signal processing circuits 5, and a black reference pixelregion (not shown) for outputting optical black that serves as thereference for black levels. The black reference pixel region is normallyformed in the outer periphery of the effective pixel region.

Based on a vertical synchronization signal, a horizontal synchronizationsignal, and a master clock, the control circuit 8 generates a clocksignal, a control signal, and the like that serve as the references foroperation of the vertical drive circuit 4, the column signal processingcircuits 5, the horizontal drive circuit 6, and the like. The clocksignal, the control signal, and the like generated by the controlcircuit 8 are input to the vertical drive circuit 4, the column signalprocessing circuits 5, the horizontal drive circuit 6, and the like.

The vertical drive circuit 4 is formed with a shift register, forexample, and selectively scans the respective pixels 2 in the pixelregion 3 sequentially in the vertical direction by the row. Pixelsignals that are based on the signal charges generated in accordancewith the amounts of light received by the photodiodes of the respectivepixels 2 are then supplied to the column signal processing circuits 5through vertical signal lines 9.

The column signal processing circuits 5 are provided for the respectivecolumns of the pixels 2, for example, and each of the column signalprocessing circuits 5 performs signal processing such as denoising andsignal amplification through correlated double sampling to calculate adifference between a reset level and a signal level in eachcorresponding pixel column, on the signal output from the pixels 2 ofeach corresponding row. Horizontal select switches (not shown) areprovided between the output stages of the column signal processingcircuits 5 and a horizontal signal line 10.

The horizontal drive circuit 6 is formed with a shift register, forexample, sequentially selects the respective column signal processingcircuits 5 by sequentially outputting horizontal scan pulses, and causesthe respective column signal processing circuits 5 to output pixelsignals to the horizontal signal line 10.

The output circuit 7 performs signal processing on signals sequentiallysupplied from the respective column signal processing circuits 5 throughthe horizontal signal line 10, and outputs the processed signals.

[1-2. Structures of Main Components]

FIG. 2 shows the structure of the pixel region 3 of the solid-stateimaging device 1 of this embodiment in cross-section. The solid-stateimaging device 1 of this embodiment is a CMOS solid-state imaging deviceof a back-illuminated type, for example. In the description below, afirst conductivity type is the n-type, and a second conductivity type isthe p-type.

As shown in FIG. 2 , the solid-state imaging device 1 of this embodimentincludes a substrate 12 that includes photoelectric conversion units 16provided for the respective pixels 2 and pixel transistors Tr, and aninterconnect layer 20 provided on the surface side of the substrate 12.The solid-state imaging device 1 of this embodiment also includes aspectral unit (hereinafter referred to as color filter layers 23)provided on the back surface side of the substrate 12. The solid-stateimaging device 1 of this embodiment further includes a device isolatingportion 27 that isolates the pixels 2 from one another.

The substrate 12 is formed with a semiconductor substrate made ofsilicon, and has a thickness of 1 to 6 for example. The substrate 12 isformed with a semiconductor substrate of the first conductive type orthe n-type, for example, and well regions 13 formed with impurityregions of the second conductivity type or the p-type, for example, areformed in the surface region of the substrate 12 on which the pixeltransistors Tr are formed. In this p-type well regions 13, n-typesource/drain regions 17 forming the respective pixel transistors Tr areformed. The pixels 2 provided in the pixel region 3 are arranged in atwo-dimensional matrix fashion, and each two adjacent photoelectricconversion units 16 are electrically isolated from each other by thedevice isolating portion 27. Although not shown in FIG. 2 , a peripheralcircuit unit is formed in the peripheral region of the pixel region 3.

The photoelectric conversion units 16 are provided for the respectivepixels 2 in one-to-one correspondence. The photoelectric conversionunits 16 are formed with p-type semiconductor regions 15 formed on thesurface side of the substrate 12, and n-type semiconductor regions 14provided from the depth of the back surface of the substrate 12 to thedepth of the p-type semiconductor regions 15. In each of thephotoelectric conversion units 16, the principal portion of thephotodiode is formed with the pn junction between the p-typesemiconductor region 15 and the n-type semiconductor region 14.

In each of these photoelectric conversion units 16, signal charges inaccordance with amounts of incident light are generated, and areaccumulated in the n-type semiconductor region 14. As the p-typesemiconductor regions 15 are provided in the surface of the substrate12, generation of dark current in the surface of the substrate 12 isrestrained.

Each of the pixel transistors Tr is formed with a source/drain region 17provided on the surface side of the substrate 12, and a gate electrode22 provided on the surface of the substrate 12 via a gate insulatingfilm not shown in the drawing. Each of the source/drain regions 17 isformed with a high-density n-type semiconductor region provided in thecorresponding well region 13, and is formed by ion implantation of ann-type impurity from the surface of the substrate 12.

The gate electrodes 22 are made of polysilicon, for example. Transfertransistors, amplifying transistors, reset transistors, selecttransistors, and the like are formed as the pixel transistors Tr thatdrive the pixels 2, but FIG. 2 shows only the transfer transistors asthe pixel transistors Tr. Accordingly, the source/drain regions 17 shownin FIG. 2 are equivalent to the drain regions that are the floatingdiffusion regions forming the transfer transistors.

The color filter layers 23 are made of an organic material, for example,and are provided on the back surface side of the substrate 12 via aback-surface-side fixed charge film 28 having negative fixed chargesdescribed later and back-surface-side insulating films 38. The materialof the back-surface-side fixed charge film 28 will be described later.The back-surface-side insulating films 38 can be made of a material witha lower refractive index than the color filter layers 23 and thesubstrate 12, and be made of SiO₂, SIN, or the like.

The color filter layers 23 are provided for the respective photoelectricconversion units 16, and a filter layer that selectively passes light ofR (red), G (green), or B (blue) is provided for each pixel 2. Light of adesired wavelength is transmitted through the color filter layers 23,and the transmitted light enters the photoelectric conversion units 16in the substrate 12.

The device isolating portion 27 is formed with a groove portion 24formed to extend from the surfaces of the color filter layers 23 to apredetermined depth in the substrate 12, and anegative-fixed-charge-containing film (hereinafter referred to as thein-groove fixed charge film 26) and an insulating film 25 that areburied in the groove portion 24 in this order. The device isolatingportion 27 is formed in a grid-like pattern, and is designed to isolatethe pixels 2 from one another.

The groove portion 24 is formed to extend from the surfaces of the colorfilter layers 23 to the well regions 13 in which the source/drainregions 17 of the pixel transistors Tr in the substrate 12 are formed,but not to reach the source/drain regions 17.

The in-groove fixed charge film 26 is formed to cover the inner wallsurfaces of the groove portion 24 on the side of the substrate 12. Inthis embodiment, the back-surface-side fixed charge film 28 and thein-groove fixed charge film 26 are formed with an insulating filmcontaining fixed charges (negative fixed charges in this embodiment) ofthe same polarity as the signal charges stored in the photoelectricconversion units 16. Further, in this embodiment, the in-groove fixedcharge film 26 forming the device isolating portion 27 is made of amaterial with a lower refractive index than the materials forming thesubstrate 12 and the color filter layers 23.

The insulating film containing negative fixed charges may be a hafniumoxide (HfO₂) film, an aluminum oxide (Al₂O₃) film, a zirconium oxide(ZrO₂) film, a tantalum oxide (Ta₂O₅) film, or a titanium oxide (TiO₂)film, for example. Examples of methods of forming this insulating filminclude a chemical vapor deposition technique (CVD technique), asputtering technique, an atomic layer deposition technique (ALDtechnique), and the like. By using an atomic layer deposition method, aSiO₂ film that is approximately 1 nm and reduces interface states duringfilm formation can be formed at the same time. Examples of materialsother than the above include lanthanum oxide (La₂O₃), praseodymium oxide(Pr₂O₃), cerium oxide (CeO₂), neodymium oxide (Nd₂O₃), promethium oxide(Pm₂O₃), and the like. Examples of such materials further includesamarium oxide (Sm₂O₃), europium oxide (Eu₂O₃), gadolinium oxide(Gd₂O₃), terbium oxide (Tb₂O₃), dysprosium oxide (Dy₂O₃), and the like.Examples of such materials further include holmium oxide (Ho₂O₃),thulium oxide (Tm₂O₃), ytterbium oxide (Yb₂O₃), lutetium oxide (Lu₂O₃),yttrium oxide (Y₂O₃), and the like. Further, the above insulating filmcontaining negative fixed charges may be formed with a hafnium nitridefilm, an aluminum nitride film, a hafnium oxynitride film, or analuminum oxynitride film.

Silicon (Si) or nitrogen (N) may be added to the insulating filmcontaining negative fixed charges, without degrading insulationproperties. The density of the silicon or nitrogen to be added isdetermined so as not to degrade the insulation properties of the film.As silicon (Si) or nitrogen (N) is added to the insulating film in thismanner, the heat-resisting properties of the insulating film and the ionimplantation blocking capability during a process can be improved.

Of the above mentioned insulating films containing negative fixedcharges, an insulating film with a lower refractive index than thematerial forming the substrate 12 can form the in-groove fixed chargefilm 26. The material of the in-groove fixed charge film 26 may be HfO₂or Ta₂O₅, for example.

As the insulating films containing negative fixed charges (the in-groovefixed charge film 26 and the back-surface-side fixed charge film 28) areformed on the inner wall surfaces of the groove portion 24 and the backsurface of the substrate 12 in this embodiment, an inversion layer isformed on the surface in contact with those insulating films containingnegative fixed charges. With this, an inversion layer with charges(holes in this embodiment) of the opposite polarity of the signalcharges is formed on the inner wall surfaces of the groove portion 24formed in the substrate 12 and on the back surface of the substrate 12,and this inversion layer restrains generation of dark current.

The insulating film 25 is formed to fill the groove portion 24 coatedwith the in-groove fixed charge film 26. The insulating film 25 is madeof an insulating material having a lower refractive index than thematerials forming the substrate 12 and the color filter layers 23 andthe fixed charge films, and may be formed with SiO₂, SiN, or the like.

Although the groove portion 24 is filled with the insulating film 25 inthis embodiment, the in-groove fixed charge film 26 may be designed tobe thick, and the groove portion 24 may be filled only with thein-groove fixed charge film 26. In this case, the in-groove fixed chargefilm should be made of a material having a lower refractive index thanthe refractive index of the color filter layers 23. Alternatively, thein-groove fixed charge film 26 may fill only the groove portion 24formed in the substrate 12, and the groove portion 24 between the colorfilter layers 23 may not be filled with anything.

The interconnect layer 20 is formed on the surface side of the substrate12, and is designed to include interconnects 19 (four layers in thisembodiment), with an interlayer insulating film 18 being interposedbetween these interconnects 19. Also, the interconnects 19 located onone another, and the interconnects 19 and the pixel transistors Tr areconnected via connection vias 21 formed in the interlayer insulatingfilm 18 as necessary.

In the solid-state imaging device 1 having the above describedstructure, the back surface side of the substrate 12 is illuminated withlight, and the light transmitted through the color filter layers 23 isphotoelectrically converted by the photoelectric conversion units 16. Inthis manner, signal charges are generated. The signal charges generatedby the photoelectric conversion units 16 are then output as pixelsignals from vertical signal lines (not shown) formed with thepredetermined interconnects 19 in the interconnect layer 20, via thepixel transistors Tr formed on the surface side of the substrate 12.

In this embodiment, the refractive indexes of the in-groove fixed chargefilm 26 and the insulating film 25 formed in the groove portion 24 arelower than the refractive indexes of the substrate 12 and the colorfilter layers 23. Accordingly, in the solid-state imaging device 1 ofthis embodiment, a light collecting tube structure is formed, with thecore being the color filter layers 23 and the photoelectric conversionunits 16 formed in the substrate 12, the cladding being the deviceisolating portion 27.

With this arrangement in the solid-state imaging device 1 of thisembodiment, light that enters the device isolating portion 27 isabsorbed by the color filter layers 23 and the substrate 12 havinghigher refractive indexes than that of the device isolating portion 27.Meanwhile, in the light incidence surface, light that enters the colorfilter layers 23 does not enter the device isolating portion 27.Therefore, light that obliquely enters a predetermined color filterlayer 23 does not enter the color filter layer 23 of an adjacent pixel2.

Furthermore, in the solid-state imaging device 1 of this embodiment, thephotoelectric conversion units 16 are electrically isolated from oneanother by the device isolating portion 27 in the substrate 12.Accordingly, the signal charges generated by a photoelectric conversionunit 16 do not leak into the photoelectric conversion unit 16 of anadjacent pixel 2. Accordingly, color mixing can be restrained.

As described above, the device isolating portion 27 formed in thisembodiment functions to optically isolate the pixels 2 from one anotheramong the color filter layers 23, and electrically isolate the pixels 2from one another among the photoelectric conversion units 16.

Also, in the device isolating portion 27, an insulating portion such asthe insulating film 25 buried in the groove portion 24 is preferablydesigned to be level with the surfaces of the color filter layers 23 inthe light incidence surface or protrude from the surfaces (the lightincidence surfaces) of the color filter layers 23. As the deviceisolating portion 27 prevents the color filter layers 23 from connectingto each other between adjacent pixels 2, optical isolation among thecolor filter layers 23 can be secured.

Also, in the solid-state imaging device 1 of this embodiment, light canbe divided by the respective pixels 2 on the incidence surface boundaryof the solid-state imaging device 1. Accordingly, light collection bysemi-spherical on-chip lenses that are used in conventional solid-stateimaging devices is unnecessary. In a case where a conventionalsolid-state imaging device is incorporated into an imaging apparatussuch as a camera, the optimum positions of on-chip lenses, color filterlayers, and photoelectric conversion units need to be corrected inaccordance with the characteristics of an optical system that is set forforming images on the solid-state imaging device.

In this embodiment, on the other hand, light can be divided by thepixels 2 on the incidence surface boundary of the solid-state imagingdevice 1. Therefore, the above correction, or pupil correction, isunnecessary. Accordingly, there is no need to change the design of thesolid-state imaging device 1 in accordance with an optical system set inan imaging apparatus in this embodiment. Also, with the use of thesolid-state imaging device 1 of this embodiment, the compatible rangebecomes wider and a higher degree of freedom is allowed for lenses inthe case of an interchangeable lens imaging apparatus or in a case wherethe eye pupil distance varies with the focal lengths of zoom lenses.

[1-3. Manufacturing Method]

Next, a method of manufacturing the solid-state imaging device 1 of thisembodiment is described. FIGS. 3A through 4E are process charts showingthe method of manufacturing the solid-state imaging device 1 of thisembodiment.

First, as shown in FIG. 3A, after the photoelectric conversion units 16and the pixel transistors Tr are formed in the substrate 12, theinterlayer insulating film 18 and the interconnects 19 are alternatelyformed on the surface of the substrate 12, to form the interconnectlayer 20. In the process charts shown in FIGS. 3A through 4F, only theinterconnect layer 20 near the surface of the substrate 12 is shown. Theimpurity regions such as the photoelectric conversion units 16 and thesource/drain regions 17, which are formed in the substrate 12, areformed by implanting ions of a predetermined impurity from the surfaceside of the substrate 12, for example.

A supporting substrate (not shown) formed with a silicon substrate isbonded to the uppermost layer of the interconnect layer 20, and thesubstrate 12 is turned upside down. The manufacturing procedures up tothis point are the same as the procedures for manufacturing aconventional solid-state imaging device of a back-illuminated type.Although not shown in the drawings, after the substrate 12 is turnedupside down, the back surface side of the substrate 12 is polished toreduce the thickness of the substrate 12 to a desired thickness.

As shown in FIG. 3A, a fixed charge film 28 a and an insulating film 38a are then formed on the entire back surface of the substrate 12, and ahard mask 29 made of SiN, for example, is formed on the insulating film38 a. The hard mask 29 is formed by forming a SiN layer on the backsurface of the substrate 12 by low-temperature CVD, and then performingetching on the SiN layer so as to leave the SiN layer only on thephotoelectric conversion units 16 of the respective pixels 2 by using aphotolithography technique. In this manner, the hard mask 29 having anopening 29 a immediately above the region in which the device isolatingportion 27 is to be formed is completed.

As shown in FIG. 3B, the groove portion 24 is then formed. The grooveportion 24 is formed by performing etching on the substrate 12 until thegroove reaches a predetermined depth via the hard mask 29 or a depth atwhich the well regions 13 are located in this embodiment. At this point,the fixed charge film 28 a and the insulating film 38 a exposed throughthe opening 29 a of the hard mask 29 are also subjected to the etching.As a result, the back-surface-side fixed charge film 28 and theback-surface-side insulating film 38 are formed in the regioncorresponding to the respective photoelectric conversion units 34 on theback surface of the substrate 12.

As shown in FIG. 3C, an in-groove fixed charge film 26 a and theinsulating film 25 are then formed in this order in the groove portion24. In this stage, the in-groove fixed charge film 26 a is first formedby using CVD, a sputtering technique, ALD, or the like, so as 5 to coverthe inner wall surfaces of the groove portion 24. The in-groove fixedcharge film 26 a formed in this stage is to form the in-groove fixedcharge film 26 shown in FIG. 2 . After that, the insulating film 25 tofill the groove portion 24 is formed by using SOG (Spin on Glass) orCVD. In this embodiment, SiO₂ is used as the insulating film 25.

At this point, the in-groove fixed charge film 26 a and the insulatingfilm 25 are also formed on the surface of the hard mask 29. Therefore,after the in-groove fixed charge film 26 a and the insulating film 25are formed, the in-groove fixed charge film 26 a and the insulating film25 formed on the hard mask surface are polished by using CMP (ChemicalMechanical Polishing) until the hard mask 29 is exposed. In this manner,the in-groove fixed charge film 26 a and the insulating film 25 areformed in the groove portion 24 as shown in FIG. 3C.

As shown in FIG. 4D, the SiN film used as the hard mask 29 is thenremoved by wet etching. In this stage, the portions of the in-groovefixed charge film 26 a protruding from the back surface of the substrate12 are also removed together with the hard mask 29, as shown in FIG. 4D.As a result, the in-groove fixed charge film 26 remains only in thegroove portion 24 formed in the substrate 12. Since theback-surface-side insulating film 38 is formed on the back surface sideof the substrate 12 at this point, the back-surface-side fixed chargefilm 28 is not removed.

As shown in FIG. 4E, the desired color filter layers 23 are then formedfor the respective pixels 2 by using a lithography technique. In thiscase, the color filter layers 23 are formed so as to fill the concaveportions formed by the substrate 12, and the in-groove fixed charge film26 and the insulating film 25 protruding from the back surface of thesubstrate 12, as shown in FIG. 4E.

After that, the color filter layers 23 are polished by using CMP untilthe in-groove fixed charge film 26 formed on the surface of theinsulating film 25 is exposed, for example. As a result, the solid-stateimaging device 1 shown in FIG. 2 is completed. Although the color filterlayers 23 are polished until the in-groove fixed charge film 26 isexposed in this embodiment, the polishing may be continued until thesurfaces of the color filter layers 23 become closer to the substrate 12than the surface of the in-groove fixed charge film 26 is.

Although the groove portion 24 formed to extend from the color filterlayers 23 to the substrate 12 is formed through one procedure in thesolid-state imaging device 1 of this embodiment, the present techniqueis not limited to that. For example, the device isolating portion 27that isolates the photoelectric conversion units 16 from one another inthe substrate 12 may be formed through a different procedure from theprocedure for forming the device isolating portion 27 that isolates thecolor filter layers 23 from one another.

In a case where the device isolating portion 27 in the substrate 12 isformed through a different procedure from the procedure for forming thedevice isolating portion 27 for the color filter layers 23, however,there might be misalignment between the device isolating portions 27 inthe boundary surfaces between the substrate 12 and the color filterlayers 23. In such a case, sensitivity loss and color mixing degradationare caused. By the method of manufacturing the solid-state imagingdevice 1 of this embodiment, the groove portion 24 forming the deviceisolating portion 27 is formed by one etching procedure. Accordingly,process differences (misalignment in the device isolating portion 27)can be made smaller, and the number of manufacturing procedures can bemade smaller, compared with those in a case where the device isolatingportion 27 in the substrate 12 is formed through a different procedurefrom the procedure for forming the device isolating portion 27 for thecolor filter layers 23.

Since the process differences can be made smaller in this embodiment,sensitivity loss and color mixing degradation can be prevented moreeffectively than in a case where the device isolating portion 27 in thesubstrate 12 is formed through a different procedure from the procedurefor forming the device isolating portion 27 for the color filter layers23.

Although an n-type semiconductor substrate is used as the substrate 12in this embodiment, a semiconductor substrate including an n-typeepitaxial layer in which impurity density becomes higher toward thesurface side may be used as the substrate 12, for example. Other thanthat, a semiconductor substrate including a p-type epitaxial layer inwhich impurity density becomes lower toward the surface side may be usedas the substrate 12. As such a semiconductor substrate is used as thesubstrate 12, electric fields can be readily formed by the transfertransistors. Accordingly, even in a case where the semiconductor layeron which the photoelectric conversion units 32 are formed is thick,signal charges can be prevented from failing to be transferred.

2. Second Embodiment: Example where a Pixel Isolating Portion isProvided on a Substrate

FIG. 5 is a cross-sectional view of the main components of a solid-stateimaging device according to a second embodiment of the presentdisclosure. The solid-state imaging device 30 of this embodiment differsfrom the first embodiment in that the in-groove fixed charge film andthe back-surface-side fixed charge film are not formed. Therefore, inFIG. 5 , the same components as those shown in FIG. 2 are denoted by thesame reference numerals as those used in FIG. 2 , and explanation ofthem is not repeated herein. Also, the entire structure of thesolid-state imaging device 30 of this embodiment is the same as thestructure shown in FIG. 1 , and therefore, explanation thereof will notbe repeated herein.

In the solid-state imaging device 30 of this embodiment, each ofphotoelectric conversion units 32 is formed with high-density p-typesemiconductor regions 31 and 15 formed on the back surface and thesurface of the substrate 12, and an n-type semiconductor region 14formed between the two p-type semiconductor regions 31 and 15. That is,in the solid-state imaging device 30 of this embodiment, the pnjunctions of the p-type semiconductor regions 31 and 15 and the n-typesemiconductor regions 14 form principal photodiodes.

Also, in the solid-state imaging device 30 of this embodiment, a pixelisolating portion 34 formed with a p-type semiconductor region is formedso as to isolate the photoelectric conversion units 32 from one anotherin the substrate 12, as shown in FIG. 5 . The pixel isolating portion 34is formed to extend from the back surface of the substrate 12 to thedepth of the well regions 13 in which the source/drain regions 17 of thepixel transistors Tr are formed, for example.

In this embodiment, a device isolating portion 33 is formed inside thepixel isolating portion 34 designed to isolate the photoelectricconversion units 32 from one another in the substrate 12. That is, inthe substrate 12, the side peripheral surfaces of the device isolatingportion 33 are covered with the p-type semiconductor region forming thepixel isolating portion 34. In this embodiment, the device isolatingportion 33 is also formed to extend to the depth of the well regions 13in which the source/drain regions 17 of the pixel transistors Tr areformed.

The pixel isolating portion 34 and the p-type semiconductor regions 31can be formed by implanting ions of a p-type impurity at high densityfrom the surface of the substrate 12 before the interconnect layer 20 isformed. Alternatively, the pixel isolating portion 34 and the p-typesemiconductor regions 31 may be formed by implanting ions of a p-typeimpurity at high density from the back surface side of the substrate 12after the interconnect layer 20 is formed on the surface of thesubstrate 12, the substrate 12 is turned upside down, and the substrate12 is subjected to film thinning treatment.

In the solid-state imaging device 30 of this embodiment, the deviceisolating portion 33 is formed with the groove portion 24 formed toextend from the color filter layers 23 to a predetermined depth in thesubstrate 12, and the insulating film 25 buried in the groove portion24. This insulating film 25 can be made of the same material as theinsulating film 25 of the first embodiment. That is, in the solid-stateimaging device 30 of this embodiment, insulating films containingnegative fixed charges are not formed on the inner wall surfaces of thedevice isolating portion 27 and the back surface of the substrate 12.

Since the p-type semiconductor regions 31 and 15 are formed on the backsurface and the surface of the substrate 12 in the solid-state imagingdevice 30 of this embodiment, dark current to be generated in theinterfaces of the substrate 12 can be reduced. Furthermore, as thegroove portion 24 forming the device isolating portion 33 is surroundedby p-type semiconductor regions (the pixel isolating portion 34 and thewell regions 13), dark current to be generated in the inner wallsurfaces of the groove portion 24 can be reduced.

As described above, in this embodiment, the groove portion 24 issurrounded by the p-type semiconductor regions that form the pixelisolating portion 34 and the well regions 13, and the p-typesemiconductor regions 31 are also formed on the back surface of thesubstrate 12. Accordingly, in the interfaces of the substrate 12, darkcurrent can be reduced by the layers of the opposite polarity of thepolarity of the signal charges to be generated by the photoelectricconversion units 32, and there is no need to form insulating films thatcontain negative fixed charges and cover the inner wall surfaces of thegroove portion 24 and the back surface of the substrate 12 in thisembodiment.

Since there is no need to form insulating films containing negativefixed charges in the solid-state imaging device 30 of this embodiment,the procedures for forming the insulating films containing negativefixed charges can be skipped in the procedures of the first embodimentshown in FIGS. 3C and 4E. In this embodiment, the device isolatingportion 33 is also formed to extend from the color filter layers 23 to apredetermined depth in the substrate 12, and accordingly, the sameeffects as those of the first embodiment can be achieved.

In this embodiment, insulating films containing negative fixed chargesmay also be formed on the inner wall surfaces of the groove portion 24and the back surface of the substrate 12, as in the first embodiment. Insuch a case, the hole pinning effect of the insulating films containingnegative fixed charges becomes greater, and accordingly, the darkcurrent reducing effect also becomes greater. In a case where insulatingfilms containing negative fixed charges are formed on the inner wallsurfaces of the groove portion 24 and the back surface of the substrate12 in this embodiment, the impurity densities in the p-typesemiconductor region forming the pixel isolating portion 34 and thep-type semiconductor regions 31 forming the photoelectric conversionunits 32 can be made lower.

Also, in this embodiment, a conductive film such as an ITO film may beburied in the groove portion 24 via an insulating film, and a negativepotential may be applied to the conductive film. In this case, holes aregenerated in the inner wall surfaces of the groove portion 24, andaccordingly, dark current can be reduced.

3. Third Embodiment: (First) Example where a Device Isolating Portion isHollow

Next, a solid-state imaging device according to a third embodiment ofthe present disclosure is described. FIG. 6 is a cross-sectional view ofthe main components of the solid-state imaging device 40 of thisembodiment. This embodiment differs from the second embodiment in thatthe in-groove fixed charge film and the insulating film that cover theinner wall surfaces of the groove portion 24 are not provided.Therefore, in FIG. 6 , the same components as those shown in FIGS. 2 and5 are denoted by the same reference numerals as those used in FIGS. 2and 5 , and explanation of them is not repeated herein. Also, the entirestructure of the solid-state imaging device 40 of this embodiment is thesame as the structure shown in FIG. 1 , and therefore, explanationthereof will not be repeated herein.

[3-1. Structures of Main Components]

In the solid-state imaging device 40 of this embodiment, the grooveportion 24 is hollow, and the unfilled groove portion 24 forms a deviceisolating portion 43. In the solid-state imaging device 40 of thisembodiment, the groove portion 24 is formed in the pixel isolatingportion 34 formed with a p-type semiconductor region, as in the secondembodiment. As the groove portion 24 is formed in the pixel isolatingportion 34 formed with a p-type semiconductor region, dark current to begenerated in the inner wall surfaces of the groove portion 24 can bereduced.

[3-2. Manufacturing Method]

Next, a method of manufacturing the solid-state imaging device 40 ofthis embodiment is described. FIGS. 7A and 7B are process charts showingthe method of manufacturing the solid-state imaging device 40 of thisembodiment.

First, as shown in FIG. 7A, after the photoelectric conversion units 16,the pixel isolating portion 34, and the pixel transistors Tr are formedin the substrate 12, the interlayer insulating film 18 and theinterconnects 19 are alternately formed on the surface of the substrate12, to form the interconnect layer 20. In the process charts shown inFIGS. 7A and 7B, only the interconnect layer 20 near the surface of thesubstrate 12 is shown. The impurity regions such as the photoelectricconversion units 16, the pixel isolating portion 34, and thesource/drain regions 17, which are formed in the substrate 12, areformed by implanting ions of a predetermined impurity from the surfaceside of the substrate 12.

A supporting substrate (not shown) formed with a silicon substrate isbonded to the uppermost layer of the interconnect layer 20, and thesubstrate 12 is then turned upside down. The manufacturing procedures upto this point are the same as the procedures for manufacturing aconventional solid-state imaging device of a back-illuminated type.Although not shown in the drawings, after the substrate 12 is turnedupside down, the back surface side of the substrate 12 is polished toreduce the thickness of the substrate 12 to a desired thickness. Thepixel isolating portion 34 may be formed by implanting ions of a p-typeimpurity at a desired depth from the back surface side of the substrate12 after the substrate 12 is thinned.

After that, as shown in FIG. 7A, the fixed charge film 28 a to be theback-surface-side fixed charge film 28 is formed on the back surface ofthe substrate 12, and the color filter layers 23 are formed on the fixedcharge film 28 a. The fixed charge film 28 a is formed by using CVD, asputtering technique, ALD, or the like. The color filter layers 23 areformed for the respective pixels by using a lithography technique. Sincethe procedure for removing the fixed charge film between the colorfilter layers 23 as shown in FIG. 4D is not carried out in thisembodiment, the back-surface-side insulating film 38 shown in FIG. 4D isunnecessary.

As shown in FIG. 7B, a hard mask 44 formed with an inorganic film thathas an opening portion 44 a immediately above the region to form thegroove portion 24 is then formed over the color filter layers 23. Thehard mask 44 is formed by forming a SiN layer over the color filterlayers 23, and then performing etching so as to leave the SiN layer onthe photoelectric conversion units 16 of the respective pixels 2 byusing a photolithography technique.

Etching is then performed via the hard mask 44, to form the grooveportion 24. The groove portion 24 is formed by performing etching on thesubstrate 12 until the groove reaches a predetermined depth via the hardmask 44 or a depth at which the well regions 13 are located in thisembodiment. At this point, the fixed charge film 28 a exposed throughthe opening 29 a of the hard mask 29 is also subjected to the etching.As a result, the back-surface-side fixed charge film 28 is formed in theregion corresponding to the respective photoelectric conversion units 34on the back surface of the substrate 12. After that, the hard mask 44 isremoved, and the solid-state imaging device 40 of this embodiment shownin FIG. 6 is completed.

Although not shown in the drawings, a passivation film may be formed soas to cover the inner wall surfaces of the groove portion 24 and thesurfaces of the color filter layers 23, as necessary. The passivationfilm can be formed by using low-temperature CVD, for example.

In the solid-state imaging device 40 of this embodiment, the deviceisolating portion 43 is formed with the hollow groove portion 24.Therefore, at the time of packaging, this hollow groove portion 24 isfilled with air. Air has a lower refractive index than the color filterlayers 23 made of an organic material and the substrate 12 made ofsilicon. Accordingly, in this embodiment, a light collecting tubestructure is formed as in the first embodiment, with the core being thephotoelectric conversion units 16 and the color filter layers 23, thecladding being the groove portion 24 (the device isolating portion 43).

Therefore, light that obliquely enters the surface of a predeterminedcolor filter layer 23 does not enter the color filter layer 23 of anadjacent pixel 2 among the color filter layers 23. Furthermore, thesignal charges generated by a photoelectric conversion unit 16 in thesubstrate 12 do not leak into the photoelectric conversion unit 16 of anadjacent pixel 2. As described above, the device isolating portion 43formed in this embodiment functions to optically isolate the pixels 2from one another among the color filter layers 23, and electricallyisolate the pixels 2 from one another among the photoelectric conversionunits 16, as in the first embodiment.

As there is no need to bury a fixed charge film in the groove portion 24in the solid-state imaging device 40 of this embodiment, the number ofprocedures can be reduced. Although the SiO₂ layer formed as the hardmask 44 is removed in this embodiment, the hard mask 44 can remain as alow reflecting coating when the material and the thickness of theinorganic film forming the hard mask 44 are appropriately selected. Inthis case, the inorganic film used as the hard mask 44 may be made of asingle material, or may be formed with a film stack of films made ofdifferent materials, such as a film stack of a SiO₂ film and a SiN film.

[3-3. Modification]

Next, another example of the method of manufacturing the above describedsolid-state imaging device 40 according to the third embodiment isdescribed as a modification. FIG. 8 is a diagram showing one procedurein the method of manufacturing the solid-state imaging device 40according to the modification.

In the modification, the procedures up to the formation of a fixedcharge film on the back surface of the substrate 12 are the same asthose of the third embodiment, and the procedure for forming the grooveportion 24 differs from that of the third embodiment. Therefore,explanation of the procedures up to the formation of theback-surface-side fixed charge film 28 on the back surface of thesubstrate 12 is not repeated herein.

As shown in FIG. 8 , in the modification, the fixed charge film 28 a tobe the back-surface-side fixed charge film 28 is formed on the backsurface of the substrate 12, and the color filter layers 23 having anopening 23 a immediately above the region forming the groove portion 24are then formed by using a photolithography technique. In this manner,the color filter layers 23 are formed at a distance from one pixel toanother. As the color filter layers 23 formed as shown in FIG. 8 serveas a mask, etching is performed on the back-surface-side fixed chargefilm 28 and the substrate 12, to complete the solid-state imaging device40 shown in FIG. 6 .

As described above, the number of procedures can be reduced by using thecolor filter layers 23 as a mask and forming the groove portion 24 afterthe patterning of the color filter layers 23 is performed.

4. Fourth Embodiment: (Second) Example where a Device Isolating Portionis Hollow

Next, a solid-state imaging device according to a fourth embodiment ofthe present disclosure is described. FIG. 9 is a cross-sectional view ofthe main components of the solid-state imaging device 50 of thisembodiment. The solid-state imaging device 50 of this embodiment differsfrom the solid-state imaging device 40 according to the third embodimentin that the pixel isolating portion is not formed, and an in-groovefixed charge film 51 to cover the inner wall surfaces of the grooveportion 24 is provided. Therefore, in FIG. 9 , the same components asthose shown in FIGS. 2 and 6 are denoted by the same reference numeralsas those used in FIGS. 2 and 6 , and explanation of them is not repeatedherein. Also, the entire structure of the solid-state imaging device 50of this embodiment is the same as the structure shown in FIG. 1 , andtherefore, explanation thereof will not be repeated herein.

In the solid-state imaging device 50 of this embodiment, a deviceisolating portion 52 is formed with the groove portion 24 formed toextend from the surfaces of the color filter layers 23 to the wellregions 13 in the substrate 12, and an in-groove fixed charge film 51provided to cover the groove portion 24. In this embodiment, thein-groove fixed charge film 51 is also formed on the surfaces of thecolor filter layers 23.

This in-groove fixed charge film 51 is formed so as to cover the innerwall surfaces of the groove portion 24 and the surfaces of the colorfilter layers 23 after the groove portion 24 is formed in the samemanner as in FIG. 7B. In this embodiment, the in-groove fixed chargefilm 51 is made of a material that has a lower refractive index than therefractive index of the color filter layers 23 and contains negativefixed charges.

In the solid-state imaging device 50 of this embodiment, a pixelisolating portion formed with a p-type semiconductor region is notformed in the substrate 12, but the inner wall surfaces of the grooveportion 24 are covered with the in-groove fixed charge film 51.Accordingly, dark current generation in the interfaces of the grooveportion 24 can be restrained.

Although the pixel isolating portion formed with a p-type semiconductorregion is not provided in the substrate 12 in this embodiment, the pixelisolating portion may be formed, and the groove portion 24 may be formedin the pixel isolating portion as in the third embodiment. In such acase, the hole pinning effect of the in-groove fixed charge film 51 isincreased, and generation of dark current can be more effectivelyrestrained. In addition to the above effects, this embodiment canachieve the same effects as those of the first through thirdembodiments.

5. Fifth Embodiment: Example where the Color Filter Layers are MadeThicker

Next, a solid-state imaging device according to a fifth embodiment ofthe present disclosure is described. FIG. 10 is a cross-sectional viewof the main components of the solid-state imaging device 60 of thisembodiment. The solid-state imaging device 60 of this embodiment differsfrom the first embodiment in the structures of color filter layers 61.Therefore, in FIG. 10 , the same components as those shown in FIG. 2 aredenoted by the same reference numerals as those used in FIG. 2 , andexplanation of them is not repeated herein. Also, the entire structureof the solid-state imaging device 60 of this embodiment is the same asthe structure shown in FIG. 1 , and therefore, explanation thereof willnot be repeated herein.

In this embodiment, the thickness of the color filter layers 61 isgreater than the thickness of the color filter layers 23 of thesolid-state imaging device 1 according to the first embodiment, and is 1μm or greater. While the thickness of the color filter layers isapproximately 500 nm in a conventional solid-state imaging device, thecolor filter layers 61 in the solid-state imaging device 60 of thisembodiment has a thickness of 1 μm or greater, which is much greaterthan that in a conventional solid-state imaging device.

The pigment concentration in the color filter layers 61 may besubstantially the same as the pigment concentration in the color filterlayers 23 in the first embodiment, or may be lower than the pigmentconcentration in the color filter layers 23 in the first embodiment. Asthe pigment concentration in the color filter layers 61 is adjusted inthis manner, spectral sensitivity can also be adjusted in thisembodiment.

In this embodiment, the device isolating portion 27 is formed to extendfrom the surfaces of the color filter layers 61 to the depth at whichthe well region 13 are formed in the substrate 12, as in the firstembodiment.

The solid-state imaging device 60 of this embodiment can be manufacturedby adjusting the thickness of the hard mask 29 to 1 μm or greater in theprocedure shown in FIG. 3A in the first embodiment, for example. In thesolid-state imaging device 60 of this embodiment, the pixels 2 are alsoisolated from one another by the device isolating portion 27 in theregion extending from the color filter layers 61 to the substrate 12.Accordingly, in the solid-state imaging device 60 of this embodiment, alight collecting tube structure is formed, with the core being the colorfilter layers 61 and the photoelectric conversion units 16 formed in thesubstrate 12, the cladding being the device isolating portion 27.

In the solid-state imaging device 60 of this embodiment, the colorfilter layers 61 are made thicker, so that light that enters the deviceisolating portion 27 in the light incidence surface is sufficientlyabsorbed by the color filter layers 61 forming the core, and then entersthe photoelectric conversion units 16. Accordingly, spectralcharacteristics are improved in the solid-state imaging device 60 ofthis embodiment. With the solid-state imaging device 60 of thisembodiment, the same effects as those of the first embodiment can alsobe achieved.

6. Sixth Embodiment: Example where a Light Scattering Structure isProvided

Next, a solid-state imaging device according to a sixth embodiment ofthe present disclosure is described. FIG. 11 is a cross-sectional viewof the main components of the solid-state imaging device 70 of thisembodiment. The solid-state imaging device 70 of this embodiment differsfrom the solid-state imaging device 1 of the first embodiment in that acorrugated surface 71 is formed in the back surface of the substrate 12serving as the light incidence surface. Therefore, in FIG. 11 , the samecomponents as those shown in FIG. 2 are denoted by the same referencenumerals as those used in FIG. 2 , and explanation of them is notrepeated herein.

In the solid-state imaging device 70 of this embodiment, the backsurface of the substrate 12 serving as the light incidence surface isprocessed to have minute concavities and convexities as shown in FIG. 11, so that the corrugated surface 71 is formed in the back surface of thesubstrate 12. The corrugated surface 71 formed in the back surface ofthe substrate 12 is also designed to have such a shape as to increasethe incidence angle of incident light. This corrugated surface 71 formsa light scattering structure between the substrate 12 and the colorfilter layers 23.

In the solid-state imaging device 70 of this embodiment, after theinterconnect layer 20 is formed on the surface of the substrate 12, asupporting substrate is bonded to the surface of the interconnect layer20 on the side of the substrate 12, and the substrate 12 is turnedupside down. The corrugated surface 71 is then formed while thesubstrate 12 is subjected to film thinning treatment. When the substrate12 is subjected to film thinning treatment, the back surface of thesubstrate 12 is polished to a predetermined depth by CMP, for example.At this point, with the use of a predetermined abrasive, rough polishingis performed in the film thinning treatment. As a result, the corrugatedsurface 71 can be formed in the back surface of the substrate 12, asshown in FIG. 11 .

As the light incidence surface of the substrate 12 is the corrugatedsurface 71 in the solid-state imaging device 70 of this embodiment, theincidence angle of incident light becomes greater. In a case where thecorrugated surface 71 is designed so that light entering perpendicularlyto the light incidence surface of the substrate 12 is bent 45 degrees,for example, the optical path length in the photoelectric conversionunits 16 is 1.4 times the optical path length formed in a case wherelight enters perpendicularly. As the incidence angle of incident lightis changed in this manner, the optical path length in the photoelectricconversion units 16 can be increased, and particularly, the sensitivityto long-wavelength light (such as red) can be improved. In addition tothe above effects, the same effects as those of the first embodiment canalso be achieved with the solid-state imaging device 70 of thisembodiment.

Although the back surface of the substrate 12 is the corrugated surface71 in the solid-state imaging device 70 of this embodiment, the lightincidence surfaces of the color filter layers 23 may be corrugatedsurfaces, and the same effects as those of this embodiment can beachieved if a light scattering structure is formed on the lightincidence side of the photoelectric conversion units 16.

As the surface located between the photoelectric conversion units 16 andthe color filter layers 23 is the corrugated surface 71 in thisembodiment, the incidence angle of incident light that has passedthrough the color filter layers 23 is increased by the corrugatedsurface 71 before entering the photoelectric conversion units 16.Accordingly, only the optical path after light enters the photoelectricconversion units 16 can be made longer, without a change in the spectralpath of incident light in the color filter layers 23.

The above described corrugated surface 71 effectively increases theoptical path length in the photoelectric conversion units 16 in a casewhere long-wavelength light is photoelectrically converted. Therefore,the corrugated surface 71 may be provided only for the red pixels 2, butthe corrugated surface 71 may not be provided for the green and bluepixels.

7. Seventh Embodiment: Example where a Light Absorbing Portion isProvided

Next, a solid-state imaging device according to a seventh embodiment ofthe present disclosure is described. FIG. 12 is a cross-sectional viewof the main components of the solid-state imaging device 80 of thisembodiment. The solid-state imaging device 80 of this embodiment differsfrom the solid-state imaging device 1 of the first embodiment in thestructure of a device isolating portion 82 and a light absorbing portion83 formed on the device isolating portion 82. Therefore, in FIG. 12 ,the same components as those shown in FIG. 2 are denoted by the samereference numerals as those used in FIG. 2 , and explanation of them isnot repeated herein. Also, the entire structure of the solid-stateimaging device 80 of this embodiment is the same as the structure shownin FIG. 1 , and therefore, explanation thereof will not be repeatedherein.

In the solid-state imaging device 80 of this embodiment, the deviceisolating portion 82 is formed with the groove portion 24, and thein-groove fixed charge film 26, the insulating film 25, and anontransparent film 81, which are buried in this order in the grooveportion 24. The in-groove fixed charge film 26 is formed so as to coverthe inner wall surfaces of the groove portion 24 on the side of thesubstrate 12, and the insulating film 25 is formed in the groove portion24 so as to cover the in-groove fixed charge film 26. The insulatingfilm 25 is designed to have such a thickness as not to fill the entiregroove portion 24. The nontransparent film 81 is formed so as to fillthe groove portion 24 having the in-groove fixed charge film 26 and theinsulating film 25 formed therein.

The in-groove fixed charge film 26 and the insulating film 25 can bemade of the same material as those of the first embodiment. Thenontransparent film 81 can be made of an optically nontransparent metalmaterial such as Al or W.

The device isolating portion 82 can be formed by forming the in-groovefixed charge film 26 and the insulating film 25, etching a middle regionin the insulating film 25, and filling the formed groove with a desiredmetal material, as in the procedures in the first embodiment shown inFIGS. 3A through 4E.

The light absorbing portion 83 is formed on the device isolating portion82, and is made of polysilicon or a light absorbing material such as achalcopyrite-based material.

This light absorbing portion 83 can be formed by forming a lightabsorbing material layer on the entire surface including the deviceisolating portion 82 after the formation of the device isolating portion82, and performing etching by a photolithography technique in such amanner that the light absorbing material layer remains only on thedevice isolating portion 82. After the light absorbing portion 83 madeof a light absorbing material is formed on the device isolating portion82, the color filter layers 23 are formed in the same manner as in theprocedure shown in FIG. 4F, and the solid-state imaging device 80 ofthis embodiment is completed.

In this embodiment, the light incidence surfaces of the color filterlayers 23 are substantially level with the surface of the lightabsorbing portion 83, or are closer to the substrate 12 than the surfaceof the light absorbing portion 83 is.

As the light absorbing portion 83 is formed on the light incidencesurface side of the device isolating portion 82 in the solid-stateimaging device 80 of this embodiment, the amount of light that entersthe device isolating portion 82 can be reduced. Accordingly, thespectral characteristics in the color filter layers 23 can be improved.

Furthermore, in the solid-state imaging device 80 of this embodiment,the nontransparent film 81 made of a metal material is provided in thegroove portion 24 in the device isolating portion 82. With thisarrangement, the spectral characteristics between adjacent pixels 2 canbe further improved, and color mixing can be further reducedaccordingly. In addition to the above effects, this embodiment canachieve the same effects as those of the first embodiment.

In the solid-state imaging device 80 of this embodiment, a predeterminedpotential may be applied to the nontransparent film 81 made of a metalmaterial. As a negative potential is applied to the nontransparent film81, for example, holes are generated in the inner wall surfaces of thegroove portion 24 in the substrate 12, and accordingly, the effect toreduce dark current can be increased.

8. Eighth Embodiment: (First) Example where High-Refractive MaterialPortions Are Provided

Next, a solid-state imaging device according to an eighth embodiment ofthe present disclosure is described. FIG. 13 is a cross-sectional viewof the main components of the solid-state imaging device 90 of thisembodiment. The solid-state imaging device 90 of this embodiment differsfrom the solid-state imaging device 1 of the first embodiment in thathigh-refractive material portions 91 are formed on the color filterlayers 23. Therefore, in FIG. 13 , the same components as those shown inFIG. 2 are denoted by the same reference numerals as those used in FIG.2 , and explanation of them is not repeated herein. Also, the entirestructure of the solid-state imaging device 90 of this embodiment is thesame as the structure shown in FIG. 1 , and therefore, explanationthereof will not be repeated herein.

In the solid-state imaging device 90 of this embodiment, thehigh-refractive material portions 91 made of a material having a higherrefractive index than the device isolating portion 27 are formed on thecolor filter layers 23. The high-refractive material portions 91 can beformed with a lens material, for example. The thickness of thehigh-refractive material portions 91 may be several hundreds ofnanometers, and may be approximately equal to the width of the deviceisolating portion 27 in the direction parallel to the planar directionof the substrate 12, for example.

The device isolating portion 27 is formed to extend from the lightincidence surfaces of the high-refractive material portions 91 to thedepth of the well regions 13 in the substrate 12. That is, in thisembodiment, the high-refractive material portions 91 are isolated fromone another by the device isolating portion 27 between adjacent pixels2.

In a case where the high-refractive material portions 91 shown in FIG.13 are formed, the color filter layers 23 are first formed in the samemanner as in the procedures of the first embodiment shown in FIGS. 3Athrough 4F, and the color filter layers 23 are partially removed so thatthe surfaces of the color filter layers 23 become closer to thesubstrate 12 than the surface of the device isolating portion 27 is.After that, a lens material is applied onto the color filter layers, tocomplete the solid-state imaging device 90 shown in FIG. 13 .

In the solid-state imaging device 90 of this embodiment, the pixels 2are isolated from one another by the device isolating portion 27 in theregion extending from the high-refractive material portions 91 to thesubstrate 12. Accordingly, in the solid-state imaging device 90 of thisembodiment, a light collecting tube structure is formed, with the corebeing the high-refractive material portions 91, the color filter layers23, and the photoelectric conversion units 16 formed in the substrate12, the cladding being the device isolating portion 27.

In the solid-state imaging device 90 of this embodiment, the distancefrom the light incidence surface to the substrate is longer, because thehigh-refractive material portions 91 are provided. Therefore, light thatenters the device isolating portion 27 is sufficiently absorbed by thecolor filter layers 23 forming the core, and then enters thephotoelectric conversion units 16. Accordingly, spectral characteristicsare improved in the solid-state imaging device 90 of this embodiment.With the solid-state imaging device 90 of this embodiment, the sameeffects as those of the first embodiment can also be achieved.

9. Ninth Embodiment: (Second) Example where High-Refractive MaterialPortions Are Provided

Next, a solid-state imaging device according to a ninth embodiment ofthe present disclosure is described. FIG. 14 is a cross-sectional viewof the main components of the solid-state imaging device 100 of thisembodiment. The solid-state imaging device 100 of this embodimentdiffers from the solid-state imaging device 1 of the first embodiment inthat high-refractive material portions 101 each having a rectangularshape in cross-section are formed on the color filter layers 23.Therefore, in FIG. 14 , the same components as those shown in FIG. 2 aredenoted by the same reference numerals as those used in FIG. 2 , andexplanation of them is not repeated herein. Also, the entire structureof the solid-state imaging device 100 of this embodiment is the same asthe structure shown in FIG. 1 , and therefore, explanation thereof willnot be repeated herein.

In the solid-state imaging device 100 of this embodiment, thehigh-refractive material portions 101 formed on the color filter layers23 each have a rectangular shape in cross-section, and are provided forthe respective pixels 2. Adjacent high-refractive material portions 101are isolated from each other by a groove portion 101 a. The material ofthe high-refractive material portions 101 may be the same material asthe lens material used in conventional solid-state imaging devices.

In the solid-state imaging device 100 of this embodiment, a lightcollecting tube structure is formed, with the core being thehigh-refractive material portions 101, the color filter layers 23, andthe photoelectric conversion units 16, the cladding being the grooveportion 101 a between the adjacent high-refractive material portions 101and the device isolating portion 27. Accordingly, with the solid-stateimaging device 1 of this embodiment, the same effects as those of theeighth embodiment can also be achieved.

10. Tenth Embodiment: Example where On-Chip Lenses are Provided

Next, a solid-state imaging device according to a tenth embodiment ofthe present disclosure is described. FIG. 15 is a cross-sectional viewof the main components of the solid-state imaging device 110 of thisembodiment. The solid-state imaging device 110 of this embodimentdiffers from the solid-state imaging device 1 of the first embodiment inthat on-chip lenses 111 are provided on the color filter layers 23.Therefore, in FIG. 15 , the same components as those shown in FIG. 2 aredenoted by the same reference numerals as those used in FIG. 2 , andexplanation of them is not repeated herein. Also, the entire structureof the solid-state imaging device 110 of this embodiment is the same asthe structure shown in FIG. 1 , and therefore, explanation thereof willnot be repeated herein.

In the solid-state imaging device 110 of this embodiment, the on-chiplenses 111 provided on the color filter layers 23 are designed to havespherical surfaces so that incident light is gathered into eachcorresponding pixel 2. The on-chip lenses 111 can be formed by the samemethod as the method of manufacturing on-chip lenses of conventionalsolid-state imaging devices, after the color filter layers 23 are formedin the same manner as in the procedures of the first embodiment shown inFIGS. 3A through 4F.

In the solid-state imaging device 110 of this embodiment, incident lightcan be gathered into each corresponding pixel 2, because the on-chiplenses 111 are provided. Accordingly, light collection efficiency can beimproved, and sensitivity can be increased. In addition to the aboveeffects, the same effects as those of the first embodiment can beachieved.

In the above described first through tenth embodiments, the firstconductivity type is the n-type, the second conductivity type is thep-type, and electrons are used as signal charges. However, the presentdisclosure can also be applied in cases where holes are used as signalcharges. In such cases, the conductivity types in each of theembodiments should be reversed. Solid-state imaging devices of thepresent disclosure are not limited to the above described first throughtenth embodiments, and various combinations are possible withoutdeparting from the scope of the present disclosure.

The present disclosure is not necessarily applied to a solid-stateimaging device that senses a distribution of visible incident light andcaptures the distribution as an image, but may also be applied to asolid-state imaging device that captures a distribution of infrared raysor X-rays or the like as an image.

Furthermore, the present disclosure is not limited to solid-stateimaging devices that sequentially scan respective unit pixels in thepixel region by the row, and read pixel signals from the respective unitpixels. The present disclosure can also be applied to a solid-stateimaging device of an X-Y address type that selects desired pixels one byone, and reads signals from the selected pixels one by one. Asolid-state imaging device may be in the form of a single chip, or maybe in the form of a module that is formed by packaging a pixel unit anda signal processing unit or an optical system, and has an imagingfunction.

A solid-state imaging device of the present disclosure can be used in animaging apparatus. Here, an imaging apparatus is a camera system such asa digital still camera or a digital video camera, or an electronicapparatus that has an imaging function such as a portable telephonedevice. The form of the above described module mounted on an electronicapparatus, or a camera module, is an imaging apparatus in some cases.

11. Eleventh Embodiment: Electronic Apparatus

Next, an electronic apparatus according to an eleventh embodiment of thepresent disclosure is described. FIG. 16 is a schematic view of thestructure of the electronic apparatus 200 according to the eleventhembodiment of the present disclosure.

The electronic apparatus 200 according to this embodiment includes asolid-state imaging device 201, an optical lens 203, a shutter device204, a drive circuit 205, and a signal processing circuit 206. Theelectronic apparatus 200 of this embodiment represents an embodiment inwhich the solid-state imaging device 1 of the above described firstembodiment of the present disclosure is used as the solid-state imagingdevice 201 in an electronic apparatus (a digital still camera).

The optical lens 203 gathers image light (incident light) from an objectand forms an image on the imaging surface of the solid-state imagingdevice 201. With this, the signal charges are stored in the solid-stateimaging device 201 for a certain period of time. The shutter device 204controls the light exposure period and the light shielding period forthe solid-state imaging device 201. The drive circuit 205 supplies drivesignals for controlling signal transfer operation of the solid-stateimaging device 201 and shutter operation of the shutter device 204. Inaccordance with a drive signal (a timing signal) supplied from the drivecircuit 205, the solid-state imaging device 201 performs signaltransfer. The signal processing circuit 206 performs various kinds ofsignal processing on signals output from the solid-state imaging device201. Video signals subjected to the signal processing are stored into astorage medium such as a memory, or are output to a monitor.

In the electronic apparatus 200 of this embodiment, light collectioncharacteristics and sensitivity are improved in the solid-state imagingdevice 201, and image quality can be improved accordingly. Although thesolid-state imaging device 1 of the first embodiment is used as thesolid-state imaging device 201 in this embodiment, it is also possibleto use any of the solid-state imaging devices according to the secondthrough tenth embodiments.

The present disclosure can also be embodied in the structures describedbelow.

-   -   (1)

A solid-state imaging device including:

a substrate;

pixels each including a photoelectric conversion unit formed in thesubstrate;

a color filter layer provided on the light incidence surface side of thesubstrate; and

a device isolating portion that is formed to divide the color filterlayer and the substrate for the respective pixels, and has a lowerrefractive index than the color filter layer and the substrate.

-   -   (2)

The solid-state imaging device of (1), wherein the device isolatingportion includes a groove portion formed to extend from the color filterlayer to the substrate, and an insulating film that is buried in thegroove portion and is made of a material having a lower refractive indexthan the color filter layer and the substrate.

-   -   (3)

The solid-state imaging device of (2), wherein the device isolatingportion further includes a film between the inner wall surface of thegroove portion and the insulating film, the film being formed to coverthe inner wall surface of the groove portion, the film containing fixedcharges of the opposite polarity to the polarity of signal chargesstored in the photoelectric conversion units, the film being made of amaterial having a lower refractive index than the color filter layer andthe substrate.

-   -   (4)

The solid-state imaging device of any one of (1) through (3), whereinthe device isolating portion protrudes from the light incidence surfaceof the color filter layer.

-   -   (5)

The solid-state imaging device of any one of (1) through (4), furtherincluding a high-refractive material portion formed on the color filterlayer, the high-refractive material portion being made of a materialhaving a higher refractive index than the refractive index of the colorfilter layer, the high-refractive material portion being divided for therespective pixels.

-   -   (6)

The solid-state imaging device of any one of (1) through (5), whereinthe device isolating portion is placed in the region of the pixelisolating portion formed to divide the substrate for the respectivepixels.

-   -   (7)

The solid-state imaging device of any one of (1) through (6), furtherincluding a light scattering structure on the light incidence surfaceside of the photoelectric conversion units.

-   -   (8)

The solid-state imaging device of any one of (1) through (7), whereinthe color filter layer has a thickness of 1 μm or greater.

-   -   (9)

The solid-state imaging device of any one of (2) through (8), wherein ametal material is buried in the groove portion via the insulating film.

-   -   (10)

The solid-state imaging device of (9), wherein the metal material servesas a nontransparent film.

-   -   (11)

The solid-state imaging device of any one of (1) through (10), wherein alight absorbing portion is formed on the light incidence surface side ofthe device isolating portion.

-   -   (12)

The solid-state imaging device of any one of (1) through (11), whereinan on-chip lens is formed on the color filter layer.

-   -   (13)

The solid-state imaging device of (1), wherein the device isolatingportion is formed with a groove portion extending from the color filterlayer to the substrate.

-   -   (14)

The solid-state imaging device of any one of (1) through (13), furtherincluding a film formed to cover the inner wall surface of the grooveportion, the film containing negative fixed charges, the film being madeof a material having a lower refractive index than the color filterlayer and the substrate.

-   -   (15)

A method of manufacturing a solid-state imaging device, including:

the step of forming photoelectric conversion units in a substrate, thephotoelectric conversion units corresponding to respective pixels;

the step of forming a color filter layer on the light incidence surfaceside of the substrate; and

the step of forming a device isolating portion in the region to dividethe color filter layer and the substrate for the respective pixels, thedevice isolating portion having a lower refractive index than the colorfilter layer and the substrate, the device isolating portion beingformed prior to or after the formation of the color filter layer.

-   -   (16)

The method of (15), wherein the device isolating portion dividing thecolor filter layer for the respective pixels and the device isolatingportion dividing the substrate for the respective pixels are formed inthe same step.

-   -   (17)

The method of (15) or (16), wherein

the step of forming the device isolating portion includes:

the step of forming a groove portion, prior to the formation of thecolor filter layer, by forming a mask on the light incidence surfaceside of the substrate and performing etching on the substrate via themask, the mask having an opening in the portion corresponding to theregion in which the device isolating portion is to be formed;

the step of forming an insulating film in the groove portion formed inthe substrate and the opening of the mask; and

the step of removing the mask, and

the color filter layer is formed in a concave portion after the mask isremoved, the concave portion being formed by the substrate and theinsulating film designed to protrude from the substrate.

-   -   (18)

The method of (15) or (16), wherein the step of forming the deviceisolating portion includes the step of forming a groove portion, afterthe formation of the color filter layer, by forming a mask on the colorfilter layer and performing etching on the color filter layer and thesubstrate via the mask, the mask having an opening in the portioncorresponding to the region in which the device isolating portion is tobe formed.

-   -   (19)

The method of (15) or (16), wherein the step of forming the deviceisolating portion includes the step of performing etching on thesubstrate after the formation of the color filter layer, the mask beingthe color filter layer divided for the respective pixels and beingisolated between adjacent pixels.

-   -   (20)

An electronic apparatus including:

a solid-state imaging device; and

a signal processing circuit that processes an output signal that isoutput from the solid-state imaging device,

the solid-state imaging device including: a substrate; pixels eachincluding a photoelectric conversion unit formed in the substrate; acolor filter layer provided on the light incidence surface side of thesubstrate; and a device isolating portion that is formed to divide thecolor filter layer and the substrate for the respective pixels, and hasa lower refractive index than the color filter layer and the substrate.

REFERENCE SIGNS LIST

-   -   1, 30, 40, 50, 60, 70, 80, 90, 100, 110 Solid-state imaging        device    -   2 Pixel    -   3 Pixel region    -   4 Vertical drive circuit    -   5 Column signal processing circuit    -   6 Horizontal drive circuit    -   7 Output circuit    -   8 Control circuit    -   9 Vertical signal line    -   10 Horizontal signal line    -   11, 12 Substrate    -   13 Well region    -   14 N-type semiconductor region    -   15 P-type semiconductor region    -   16, 32 Photoelectric conversion unit    -   17 Source/drain region    -   18 Interlayer insulating film    -   19 Interconnect    -   20 Interconnect layer    -   21 Connection via    -   22 Gate electrode    -   23, 61 Color filter layer    -   23 a, 29 a Opening    -   24 Groove portion    -   25 Insulating film    -   26, 26 a In-groove fixed charge film    -   27, 33, 43, 52, 82 Device isolating portion    -   28 Back-surface-side fixed charge film    -   29, 44 Hard mask    -   31 P-type semiconductor region    -   34 Pixel isolating portion    -   71 Corrugated surface    -   81 Nontransparent film    -   83 Light absorbing portion    -   91, 101 High-refractive material portion    -   111 On-chip lens    -   200 Electronic apparatus    -   201 Solid-state imaging device    -   203 Optical lens    -   204 Shutter device    -   205 Drive circuit    -   206 Signal processing circuit

The invention claimed is:
 1. An imaging device, comprising: asemiconductor substrate; a first photoelectric conversion regiondisposed in the semiconductor substrate; a second photoelectricconversion region adjacent to the first photoelectric conversion regionand disposed in the semiconductor substrate; a first color filterdisposed above the first photoelectric conversion region in across-sectional view; a second color filter disposed above the secondphotoelectric conversion region in the cross-sectional view; and an airgap, in the cross-sectional view, disposed between the first and secondphotoelectric conversion regions and disposed between the first andsecond color filters.
 2. The imaging device of claim 1, wherein the airgap is defined by a groove that extends into the semiconductorsubstrate.
 3. The imaging device of claim 2, further comprising: a filmdisposed on inner wall surfaces of the groove.
 4. The imaging device ofclaim 3, wherein the film has a lower refractive index than the firstcolor filter and the second color filter.
 5. The imaging device of claim3, wherein the film is disposed on surfaces of the first color filterand surfaces of the second color filter.
 6. The imaging device of claim1, further comprising: an interconnect layer disposed on andelectrically connected to the semiconductor substrate.
 7. The imagingdevice of claim 6, wherein the interconnect layer comprises a firsttransfer transistor to transfer charge collected by the firstphotoelectric conversion region, and a second transfer transistor totransfer charge collected by the second photoelectric conversion region.8. The imaging device of claim 7, wherein the interconnect layer furthercomprises a reset transistor, an amplification transistor, and aselection transistor.
 9. The imaging device of claim 1, furthercomprising: a floating diffusion region disposed in the semiconductorsubstrate and that collects charge of the first photoelectric conversionregion.
 10. The imaging device of claim 9, wherein, in thecross-sectional view, the floating diffusion region is below the airgap.
 11. The imaging device of claim 10, further comprising a firstimpurity region disposed in the semiconductor substrate and having aconductivity type opposite a conductivity type of the semiconductorsubstrate, wherein the floating diffusion region comprises the firstimpurity region.
 12. The imaging device of claim 11, further comprising:a second impurity region disposed in the semiconductor substrateadjacent to the first impurity region and having a same conductivitytype as the first impurity region with a higher concentration ofimpurities than the first impurity region.
 13. The imaging device ofclaim 1, further comprising: an isolating portion disposed in thesemiconductor substrate between the first photoelectric conversionregion and the second photoelectric conversion region, wherein theisolating portion has a conductivity type opposite to a conductivitytype of the semiconductor substrate.
 14. An electronic apparatus,comprising: a signal processing circuit; and an imaging device,comprising: a semiconductor substrate; a first photoelectric conversionregion disposed in the semiconductor substrate; a second photoelectricconversion region adjacent to the first photoelectric conversion regionand disposed in the semiconductor substrate; a first color filterdisposed above the first photoelectric conversion region in across-sectional view; a second color filter disposed above the secondphotoelectric conversion region in the cross-sectional view; and an airgap, in the cross-sectional view, disposed between the first and secondphotoelectric conversion regions and disposed between the first andsecond color filters.
 15. The electronic apparatus of claim 14, whereinthe air gap is defined by a groove that extends into the semiconductorsubstrate.
 16. The electronic apparatus of claim 15, further comprising:a film disposed on inner wall surfaces of the groove.
 17. The electronicapparatus of claim 16, wherein the film has a lower refractive indexthan the first color filter and the second color filter.
 18. Theelectronic apparatus of claim 16, wherein the film is disposed onsurfaces of the first color filter and surfaces of the second colorfilter.
 19. The electronic apparatus of claim 14, further comprising: aninterconnect layer disposed on and electrically connected to thesemiconductor substrate.
 20. The electronic apparatus of claim 19,wherein the interconnect layer comprises a first transfer transistor totransfer charge collected by the first photoelectric conversion region,and a second transfer transistor to transfer charge collected by thesecond photoelectric conversion region.